The rotameter is one of the simplest and yet most widely used flowmeters available today, which comprises a vertically disposed tapered flow passage a cross sectional area progressively increasing from the inlet at the to the outlet at the top and a flow obstructing member suspended in the stream wherein the drag force exerted by the upward moving fluid counter-balance the weight of the flow obstructing member. The flow rate of the fluid is determined from the vertical position of the flow obstructing member. The majority of rotameters, however, suffer a great deficiency: They almost exclusively use a visual read-out means consisting of a graduated glass window to measure the vertical position of the flow obstructing member as a measure of flow rate of the fluid, while a few versions employing a remotely readable means for indicating the vertical position of the flow obstructing member have poor accuracy and inadequate repeatability due to lack of precision in converting the physical position of the flow obstrucing member to an electrical signal by the transducer employed therein. Because of this shortcoming, rotameters available at the present time are unsuitable for many applications, wherein the output from the rotameter has to be used as an input to the flow controlling or flow handling devices. There is a need in industrial plants as well as in scientific laboratories for a rotameter with a remote read-out means that accurately and reliably provides the rate of fluid flow in the form of an electrical signal.